This invention generally relates to humidifiers, and more particularly relates to power humidifiers of the rotary drum type adapted to be inserted in the horizontal supply duct of any forced warm air furnace.
Heating systems for homes and other structures include several basic types of units which are classified either by the type of fuel used or by the type of heat distribution system used. Included in the latter category are steam heating, hot-water heating, and forced air-heating systems. With the advent of natural fuels and efficient burning systems forced-air heating systems have become extremely popular. The heat can be more readily distributed. Also unsightly heat exchanging units are eliminated. The burner itself is more efficient resulting in less dust and soot. In addition, forced-air heating systems lend themselves to combination with central air conditioning since only one set of ducts and outlets need be provided. A further advantage of forced warm air heating systems is the lack of extensive plumbing connections which require regular maintenance.
A disadvantage in forced warm air heating systems resides in the fact that the air in the enclosed area which is being heated is usually low in moisture content. A basic relationship exists between the temperature of the air and the moisture contained therein. Relative humidity is defined as the amount of moisture in the air as compared with the amount that the air could contain at the same temperature expressed as a percentage. It therefore follows, that if cool air, which is capable of containing only a fairly low amount of moisture, at a high relative humidity, is heated, the amount of moisture in the air remains exactly the same while the amount of moisture the air could contain rises. The result of this is an extremely low relative humidity. While unusually high relative humidity causes a great deal of discomfort, it is generally acknowledged that unusually low relative humidity can be equally as uncomfortable and can cause damage to both animate and inanimate objects. If the air is too dry, wood objects tend to dry out and contract with consequent damage thereto. Such wooden objects could include furniture as well as structural members of a building. As for the effects on the occupants of a building, various sinus tissues become dry and irritated. Further, static electricity easily builds up and creates extremely uncomfortable conditions.
These various ill effects associated with heating systems can be eliminated by providing a humidifier in the horizontal supply duct of any forced warm air furnace to raise the relative humidity of the air before passing it to the enclosed area which will be heated. Basically, such a humidifying system has a water reservoir, connected to a source of supply, and a rotating drum or evaporator located in the supply duct for increasing the contact area of the air with the water. The system includes means to provide a constant source of water in the unit. With such means must be associated means for controlling the delivery of water to the unit. Various delivery means have been used, but not all of them are able to compensate for fluctuations in evaporation rate due to air velocity and/or ambient relative humidity.
Also, depending on the hardness of the water in a particular area, a buildup of minerals in the reservoir can occur, thereby necessitating frequent cleaning and perhaps even repairs. Associated with the necessity to compensate for water hardness is the necessity to control the growth of algae in the reservoir.
Another disadvantage associated with the humidifiers of the prior art concerns the means for providing a large air-water contact area. Such means are often expensive and require frequent replacement due to clogging and other lessening of efficiency. Further, such means are often extremely inaccessible, thereby requiring the help of a serviceman to perform that operation.